Lesquerella fendleri is a desert shrub native to the American Southwest. The species has been previously recognized as possessing a seed oil containing hydroxy fatty acids that have potential industrial uses. (Mikolajczak et al., JAOGS 1962, 39, 78-80). Lesquerella seed swells in water to 13 times its original volume and this occurs mainly in the seed surface gum (SSG) or capsular gel layer. Recognition that L. fendleri was a potential source of polysaccharide gums was made during a survey (Tookey and Jones, Econ. Botany, 1965, 19, 165-174) wherein the ground seeds were found to contain 19.5% gums by weight. Recovery of the gum was accomplished by hot water extraction of whole ground seeds and subsequent precipitation with ethanol. Cited values in the survey were corrected for protein content and components not hydrolyzable with dilute acid. An ash and moisture-free mucilaginous material derived from L. fendleri has been examined for use in entrapping mosquito larvae (Barber et al., Mosquito News, 1974, 34, 394-398).
Properties of acidic polysaccharide gums such as those derived from Lesquerella, depend greatly on structure and are as diverse as their compositions. Properties also change drastically in synergistic combinations with other gums (Dea; Gordon and Breach Sci. Publ., New York, N.Y., 1987). The wide variations of composition and structure within the class render each gum unique, ranging from gum arabic, an exudate, which has a low viscosity in solution to water-insoluble, capsular gels from seeds, which thicken solutions by entirely different physical mechanisms than do soluble polysaccharides. Gums have a number of commercial applications, but are used primarily to increase the viscosities of aqueous solutions or to form gels. Lesquerella gums are unique in that other gums used commercially are not extracted from oilseeds or oilseed presscake.
L. fendleri is a crucifer. Other cruciferous seed gums that have been thoroughly analyzed include Sinapis alba L. (yellow mustard) seed which has 5% mucilage, 56% of which is water soluble (Cui et al., Food Chem., 1993a, 46, 169-176). This crude mucilage was composed of 15% glucuronic and galacturonic acids, 24% glucose, 14% galactose, 6% mannose, 3% rhamnose, 3% arabinose and 1.8% xylose. Ash (15%), and protein (4.4%) were the other major components in addition to the polysaccharides. The water-soluble component was further characterized as a mixture of a pectic polysaccharide composed of galacturonic acid, galactose, and rhamnose; a .beta.-1,4-glucan; and polysaccharides composed mostly of neutral sugars with non-reducing end residues of glucuronic acid (Cui et al., Carbohydr. Polymers, 1993b, 20, 215-225). Lepidium sativum (cress) seed has a capsular gel and a water-soluble gum similar to those of lesquerella seeds, but the gums make up only 2.6% of the seed weight (Bailey, Biochem. J., 1935, 29, 2476-2485; Tyler, J. Chem. Soc., 1965, 5288-5300). Brassica sinapis alba (white mustard) also has a cold-water-soluble soluble polysaccharide that has been reported to contain as much as 50% microcrystalline cellulose in micelles (Grant et al., Chem. Commun., 1969, 805-806). Brassica campestris (rapeseed) has been shown to contain 0.25% of a complex polysaccharide mixture (Siddiqui et al., Carbohy. Res., 1977, 54, 231-236).